Skype is now allowing users to pay for WiFi access in places that charge for WiFi, such as airports, using a service called Skype Access. This past weekend Skype sponsored free WiFi at 100,000 hotspots around the world to publicize the new service.

Skype Access is designed to be an alternative to credit cards and the cumbersome task of typing in details and authenticating via login screen. It allows users to select the WiFi network they want to connect to, and if that hotspot supports Skype, a pop-up message will appear asking users to pay using their Skype credit. Once they are connected, users pay per minute for what what they use as opposed to traditional hotspot pricing that requires users to pay for at least an hour of access even if a user connects for 20 minutes. The per-minute price of Skype Access is around 19 cents.
Source: http://www.skype.com/intl/en/allfeatures/skypeaccess/